The present invention generally relates to an optical information recording/reproducing method and an apparatus for carrying out the same. More particularly, the invention is concerned with a recording system which is advantageously suited for ensuring interchangeability (compatibility) among existing recording medium of different types or between the currently used recording media and those of increased record density which will become available for practical application in the not too distant future.
In the prior art optical disk storage system, it is known that an index area is provided on a disk for storing therein data for retrieval, data for access designation and those for other purposes, as is disclosed, for example, in Japanese Patent Application Laid-Open No. 25278/1981 (JP-A-56-25278).
There are, however, established a variety of specifications for the recording system in respect to the recording light (laser) power, reflection factor of the disk and other parameters, and any given recording system is so designed to conform with one of the specifications. Consequently, a recording/reproducing apparatus designed to operate with the disk having the reflection factor of a certain predetermined value is not in the position to perform the recording/reproducing operation on another disk having a reflection factor which differs from the predetermined one. Further, a system in which a new modulation method developed with the aim to realize the high density recording is adopted is incapable of reproducing information recorded on the disk of the old type. Therefore, the disks which are currently used can no more find utility in the recording/reproducing system of the coming generation. It goes without saying that such absence of interchangeability or compatibility among the recording media provides much inconvenience. Thus, there exists a great demand for realizing the interchangeability of the recording media since otherwise the old type of disk could not be used in the future system which will no doubt adopt a novel modulation method in an effort to increase the recording density.